Severe hypoxemia after radiofrequency ablation for atrial fibrillation in palliatively repaired tetralogy of Fallot: A case report

BACKGROUND Patients with tetralogy of Fallot(TOF)often have arrhythmias,commonly being atrial fibrillation(AF).Radiofrequency ablation is an effective treatment for AF and does not usually cause severe postoperative hypoxemia,but the risk of complications may increase in patients with conditions such as TOF.CASE SUMMARY We report a young male patient with a history of TOF repair who developed severe hypoxemia after radiofrequency ablation for AF and was ultimately confirmed to have a new right-to-left shunt.The patient subsequently underwent atrial septal occlusion and eventually recovered.CONCLUSION Radiofrequency ablation may cause iatrogenic atrial septal injury;thus possible complications should be predicted in order to ensure successful treatment and patient safety.

Prospective Cohort Research of Aortic Root Dilatation after Surgical Repair in Adults with Tetralogy of Fallot(TRANSIT)

Background:Aortic root dilatation occurs in adults with tetralogy of Fallot(TOF)after surgical repair,but the longitudinal changes are unclear.The main research aim is to determine the annual dilatation rate of aorta in adults with repaired TOF.Methods:The present,multicentric,prospective cohort study assessed the rate of aortic diameter change in adults aged 20 years or older with TOF,including pulmonary artery atresia,who underwent surgical repair.Clinical data,focusing on echocardiograms,were collected at three-year intervals from seven hos-pitals.Results:In total,104 patients(58 males;median age:29 years)were enrolled.The actual Valsalva sinus(VS)diameter was 34.3±5.8(mean±standard deviation)and 36.1±6.0 mm at the initial andfinal examinations,respectively,and the annual dilatation rate was 0.64(0.07,1.33)(median,interquartile)mm/year.The corrected diameter at the respective examination was 21.3±3.8 and 22.2±3.7 mm/m^(2),and the annual dilation rate was 0.28(-0.21,0.76)mm/m^(2)/year.Multiple regression analysis showed that factors significant associated with dila-tation rate of actual VS diameter were the diastolic blood pressure(standardized coefficient-0.22;p=0.04),cardiothoracic ratio(0.28;0.02),and the ratio of early mitral valve inflow velocity to early diastolic annular velocity(E/e′)ratio(0.31;0.004).Factors significantly associated with corrected VS diameter were diastolic blood pressure(-0.25;0.02)and the E/e′ratio(0.34;0.001).Conclusions:In adults with repaired TOF,the rate of dilatation of the aortic diameter was associated with decreased diastolic blood pressure and left ventricular diastolic dysfunction,possibly reflecting decreased aortic wall elasticity.

Single-Cell RNA Sequencing Reveals Potential for Endothelial-to-Mesenchymal Transition in Tetralogy of Fallot

Background:Tetralogy of Fallot(TOF)is a very common cyanotic congenital heart disease.Endothelial-to-mesenchymal transition(EndoMT)is recognized as a physiological mechanism involved in embryonic heart development and endothelial formation.However,there is still a gap in the reports related to the mechanism of EndoMT development in TOF.Methods:First,transcriptomic data of single cell nuclei of TOF and Donor were obtained based on the Gene Expression Omnibus(GEO)database,and the data were normalized and clus-tered by dimensionality reduction using the Seurat package.Subsequently,differentially expressed genes(DEGs)between TOF and Donor were screened using the“FindMarkers”function,and the gene sets of interest were enriched.Finally,to characterize the dynamics of EndoMT occurrence in TOF,we performed pseudotime cell tra-jectory inference as well as utilized SCENIC analysis to probe the gene regulatory networks(GRNs)dominated by transcription factors(TFs)in endothelial cells.Results:We identified a total of six cell clusters based on single-cell nuclear transcriptome data from TOF and Donor.We found that 611 genes with up-regulated expression within TOF showed conversion to mesenchyme.By subdividing endothelial cell subtypes,endothelial cells 2 were shown to be involved in cell adhesion,migration and extracellular matrix processes.Pseudo-time and SCENIC analyses showed that endothelial cell 2 has EndoMT potential.In addition,ERG and TEAD1 are TFs that play key reg-ulatory roles in this subtype,and both of their target genes are also highly expressed in TOF.This demonstrates that ERG and TEAD1 effectively promote the EndoMT process.Conclusion:Our study reveals the molecular mechanisms underlying the development of EndoMT in TOF,which demonstrates that manipulating the endothelial-to-mesenchymal transition may offer unprecedented therapeutic potential for the treatment of TOF.

Pulmonary and tricuspid regurgitation after Tetralogy of Fallot repair: A case report

BACKGROUND Tetralogy of Fallot(TOF)is one of the most common congenital heart defects,and surgery is the primary treatment.There are no precise guidelines on the treatment protocol for tricuspid regurgitation(TR)as a common complication of TOF repair.The timing for treatment in patients presenting with valve regurgitation after TOF repair is often difficult to determine.Here,we report the first case of sequential treatment of pulmonary and TR using interventional therapy.CASE SUMMARY We present the case of a 52-year-old female patient,who had a history of TOF repair at a young age.A few years later,the patient presented with pulmonary and tricuspid regurgitation.The symptoms persisted and TR worsened following percutaneous pulmonary valve implantation.Preoperative testing revealed that the patient’s disease had advanced to an intermediate to advanced stage and that her general health was precarious.Because open-heart surgery was not an option for the patient,transcatheter tricuspid valve replacement was suggested.This procedure was successful,and the patient recovered fully without any adverse effects.This case report may serve as a useful resource for planning future treatments.CONCLUSION Treatment of both valves should be considered in patients with tricuspid and pulmonary regurgitations following TOF repair.The interventional strategy could be an alternative for patients with poor general health.

Pulmonary Hypertension Crisis in Patient with Tetralogy of Fallot and Mixed Total Anomalous Pulmonary Vein Connection after the Primary Correction:A Rare Case Report

Tetralogy of Fallot(TOF)with total anomalous pulmonary vein connections(TAPVC)is a rare type of complex congenital heart disease among all TOF cases.Co-presentation of major aortopulmonary collateral arteries(MAPCAs)compensates for the lack of central pulmonary bloodflow and decreases the severity of right-to-left shunting in TOF.We present a case of a 2-year-old child with complex diagnoses of TOF,TAPVC,a large secun-dum atrial septal defect(ASD),and intraoperatively identified MAPCAs.She underwent surgery to repair the TAPVC,valve-sparing reconstruction of the right ventricular outflow tract,interventricular defect closure,and the creation of patent foramen ovale(PFO).After the operation,hemodynamic instability happened along with sudden blood pressure drop,desaturation,and increased central venous pressure,which subsided after adminis-tering inhalational nitric oxide(NO).A postoperative pulmonary hypertension crisis was suggested when the patient experienced recurrent symptoms after the termination of NO.Echocardiographicfindings of a D-shaped left ventricle(LV),right-to-left PFO shunt and high tricuspid valve gradientfirmly established the diagnosis.It was subsequently managed with continuous NO inhalation and sildenafil,which rendered a satisfactory outcome.Repaired TOF and TAPVC could be at particular risk of developing pulmonary hypertension crisis,especially in the presence of MAPCAs due to possible remodeling of the pulmonary vasculature.Furthermore,a relatively non-compliant LV function and small left atrial size may exacerbate the risk of developing postcapillary pulmonary hypertension after TAPVC repair.A successful postoperative outcome calls for a meticulous preoperative analysis of the anatomical lesions,as well as careful monitoring.

Appropriate Heart Rate in a Patient with Repaired Tetralogy of Fallot

Appropriate heart rate in a failing pulmonary ventricle remains unknown, particularly in congenital heart diseasewith unique hemodynamics. A 71-year-old male with repaired tetralogy of Fallot and a pacemaker for a sinusnode dysfunction suffered from heart failure symptoms with preserved left ventricular function. Simply changingthe pacemaker’s lower rate from 60 to 75 bpm, New York Heart Association classification improved from III to II,and hemodynamic parameters drastically improved. We regarded this case as informative. Appropriate heart ratecould be higher in congenital patients with failing right and non-failing left ventricles than in adults with malfunctioningLV.

Evaluation of Right Ventricular Global Longitudinal Function in Patients with Tetralogy of Fallot by Two-dimensional Ultrasound Speckle Tracking Imaging

Quantification of right ventricular(RV)volume and function remains a challenge because of RV complex geometry by conventional echocardiography.The purpose of this study was to assess RV global longitudinal function in patients with tetralogy of Fallot(TOF)by 2-dimensional ultrasound speckle tracking imaging(STI).Thirty-eight patients with TOF were enrolled in this study and divided into child group(n=25)and adult group(n=13)according to age.Thirty-eight age-and sex-matched normal subjects were selected as c...

Anomalous origin of left pulmonary artery branch from the aorta with Fallot's tetralogy:one case report

We report the case of a ten-year-old boy who had often presented with respiratory distress since born. Chest X-ray showed an enlarged right ventricle. Echocardiography demonstrated characteristic features of Fallot＇s tetralogy and the left pulmonary artery could not be visualized. However, cardiac catheterization disclosed that the left pulmonary artery had an anomalous origin in the ascending aorta. The patient underwent total surgical correction of the defects. Nine days later, he was discharged. We present the results of a literature review of the incidence, physiopathological, clinical, diagnostic, and surgical characteristics of this rare disease.

Surgical Treatment of Tetralogy of Fallot with Pulmonary Valve Agenesis in a 22 Years Old Patient

Agenesis of pulmonary valve is a rare variant and severe form of Tetralogy of Fallot (ToF). The evolution is usually marked by respiratory and cardiac failure at early age, which needs early surgical correction. Uncorrected treatment of Tetralogy of Fallot diagnosed at adult age is infrequent and only few studies have been described. We present here a rare case of a 22 years old patient who presented with dyspnea since childhood. Subsequent investigations allowed diagnosis of treatment of Tetralogy of Fallot with agenesis of the pulmonary valve. Following the assessment, the patient underwent a surgical repair and the recovery was uneventful. The management of treatment of Tetralogy of Fallot with pulmonary valve agenesis in adult period remains complex, requiring different surgical techniques.

Pulmonary Perfusion Asymmetry in Patients after Repair of Tetralogy of Fallot: A 4D Flow MRI-Based Study

Background:Repaired Tetralogy of Fallot(rTOF)patients may have residual lesions such as main(MPA)and branch pulmonary artery stenosis(BPAS).While MPA stenosis is well studied,few data are available on BPAS in rTOF.We aimed to describe pulmonary perfusion in a large paediatric cohort of rTOF and its impact on right ventricular and outflow-tract hemodynamics using 4D flow CMR.Methods:130 consecutive patients(mean age at CMR 14.3±4.6 years)were retrospectively reviewed.96 patients had transannular patch without valve preservation while 34 patients had conserved annulus or valved conduit.A pulmonary blood flow ratio(right pulmonary artery(RPA)/left pulmonary artery(LPA))between 0.75 and 1.56 was considered normal.Results:Asymmetric pulmonary perfusion was present in 59/130 patients(45%),with 54/59(91%)having left lung hypoperfusion(blood flow ratio>1.56).RPA/LPA perfusion ratio in the whole cohort was independently associated with the LPA Z-score(−0.053,p=0.007),the RPA regurgitant fraction(RF)(0.013,p=0.011)and previous LPA stenting(0.648,p=0.004).Decreasing LPA%perfusion(and conversely increasing RPA%perfusion)was significantly associated with higher MPA diameter Z-score(−0.06,p=0.007).On multivariate analysis,MPA Z-score was independently associated with pulmonary RF(0.48,p<0.001)and with right ventricular indexed volumes(coefficient 3.6,p=0.023).In patients with transannular patch repair,asymmetric pulmonary flow was an independent predictor of right ventricular ejection fraction(RVEF)(−3.66,p=0.04).Conclusions:Pulmonary perfusion asymmetry is frequent in rTOF and is associated with abnormal right ventricular and outflow-tract hemodynamics,including MPA dilatation and decreased RVEF in patients after transannular patch.

Relation or Influence of RVOTO in the Inflammatory Response to Reoxygenation in Patients with Tetralogy of Fallot

Background:This study evaluated differential inflammatory response to cardiopulmonary bypass reoxygenation in tetralogy of Fallot repair.Methods:We performed a retrospective study at a cardiovascular center from 2012 to 2018,including 500 patients aged 1 week–18 years who received complete repair of tetralogy of Fallot.Patients were grouped according to tertiles of preoperative RVOT gradient on echocardiography into mild,moderate,and severe stenosis.We measured the highest perfusate oxygenation(PpO_(2))during aortic occlusion as independent variable.Primary outcome was systemic inflammatory response syndrome(SIRS)within 7 days postoperatively or the time of death or discharge.Results:Overall,rate of SIRS was 24.2% without significant differences among three groups(P>0.05).Older age,male,and smaller indexed left ventricular end-diastolic volume is independent risk factor of SIRS.There were significant interactions between RVOT stenosis and PpO2 on SIRS(P interaction=0.011):higher PpO_(2) was associated with a greater SIRS risk among combined moderate and severe stenotic children(OR 1.46395%CI[1.080,1.981]per-SD increase,P=0.014)but not among mild stenotic children(OR 0.900[0.608,1.333]per-SD increase;P=0.600),independent of covariates.Conclusion:The association of PpO_(2) with SIRS was modified by RVOT obstruction severity in tetralogy of Fallot repair.

Contemporary Patterns of Management of Tetralogy of Fallot:Data from a Single Center in China

Background:There is scarce research on large cohorts with tetralogy of Fallot(TOF)from China.The database in Fuwai Hospital was reviewed to ascertain current trends in the management of TOF and to determine the prevalence of various surgical techniques and the optimal early outcome.Methods:This cross-sectional study included 1861 patients who underwent surgery between 2012 and 2017 and were aged 0-18 years old with a primary diagnosis of TOF.A total of 1760 eligible patients were included in the analyses.Results:A total of 1683 patients underwent repair of TOF as a one-stage operation(primary repair).Sixty-one patients underwent repair of TOF after prior palliation.Of patients who underwent one-stage repair(n=1683):858 were 6 months to 1 year old,421 were 1 to 2 years old,251 were 2-18 years old,and 145 were 3 to 6 months old.Of patients who underwent repair following prior palliation(n=61),58(95.1%)were older than 1 year of age.Of 1744 complete repairs,986(56.0%)had annulus-sparing(AS)repair.Total in-hospital mortality was 15 of 1744(0.9%)for complete repair(including one-stage and staged repairs).The total incidence of the optimal early outcome was 78.2%in terms of a composite of the absence of death in the first year,significant right ventricular outflow tract obstruction,significant pulmonary valve insufficiency,or catheter or surgical reintervention.Conclusions:Surgical correction in patients with TOF can achieve an acceptable outcome in terms of death and reintervention.Primary repair at 6 months to 1 year of age is the most prevalent strategy in our centre.However,the relatively high incidence of early undesirable surgical adequacy of the pulmonary valve(PV)represents a wake-up call.

Growth of the Pulmonary Valve Annulus after the Modified Blalock-Taussig Shunt in Patients with Tetralogy of Fallot

Background:The surgical outcomes of tetralogy of Fallot(TOF)have evolved dramatically and have resulted in lower mortality rate.Currently,the many cardiac centers have a trend to early single-stage complete repair more than a staged repair.However,the patients who have an early primary repair were required transannular patch augmentation of a pulmonary valve frequently.This effect has been developed a chronic pulmonary insufficiency may lead to right ventricular dilation,dysfunction.In this era,the aim of treatment of TOF is attempted to preserve pulmonary valve annulus for prevent right ventricular dysfunction in the future.The systemic to pulmonary artery shunt is a palliative procedure or known as staged repair for symptomatic patients with TOF.The modified Blalock-Taussig shunt(mBTS)is the most useful systemic to pulmonary shunt and perform as an initial procedure before complete repair.The mBTS can provide increase pulmonary blood flow as well as improve oxygenation and also promote pulmonary artery(PA)growth.However,the effect of this procedure to promote growth of a pulmonary valve annulus is still debate.Objectives:To compare a growth of pulmonary valve annulus between after staged repair and primary repair in patients with TOF(without pulmonary atresia).Methods:A retrospective case-control study,review of patients with TOF underwent total repair at our hospitals from January 2005 and December 2017 was performed,a total number of 112 patients underwent TOF repair.Twenty-nine patients(26%)underwent a staged repair(mBTS group)and 83(74%)underwent total repair only or primary repair(PR group).We evaluated diameter of pulmonary valve annulus by using echocardiography at the time of first diagnosis and before complete repair on both groups.Results:The age of diagnosis of mBTS group were younger than PR group(p=0.011).Therefore,pulmonary valve annuls were smaller in mBTS group.(Z-score,−2.93±1.42 vs.−1.89±0.97;p=0.001).However,the growth potential of pulmonary valve annulus was increase more than PR group significantly(Z-score,−1.46±1.02 vs.−2.11±1.19;p=0.009)Even though a patent ductus arteriosus was found commonly in PR group(p=0.018).Conclusions:Our results suggest the systemic to pulmonary shunt or mBTS can promote growth of pulmonary valve annulus in patients with TOF.

MORPHOMETRIC ANALYSIS OF LUNG BIOPSY TISSUE IN PATIENTS WITH TETRALOGY OF FALLOT AND VENTRICULAR SEPTAL DEFECT WITH PULMONARY HYPERTENSION

The pulmonary vasculature from 24 children with Tetralapy of Fallot (TOF)and ventricular septal defect with pulmonary hypertension (VSD/PH) war studied morphometrically. The study showed hypoplasis of small arteries in TOF There was a decrease in pulmonary artery size, but in the intra-acinar region small arteries were increased in number with mild intimal change. The pulmonary vascular resistance was normal postoperatively. The pulmonary vasculature in VSD/PH displayed a variable degree of obstructive lesions. The pulmonary arterial pressure remained elevated postoperatively in patients with severe pulmonary obstructive diseases.

A Case Report of Pediatric Cerebral Venous Thrombosis with Undiagnosed Complex Congenital Heart Disease: Tetralogy of Fallot with OS ASD: A Cataclysmic Ending

Cerebral Venous Sinus Thrombosis (CVST/CSVT) is occlusion of cerebral veins and venous sinuses of brain secondary to blood clot formation resulting in hindrance in the blood drainage system in brain, leading to disturbances the internal homeostasis of brain, raised intracranial pressure, cerebral edema, and 50% of cases will have venous infarction or venous hemorrhage (stroke). CVST although being a Rare disorder but may be more common in children than adults with greater risk in neonatal period i.e. first 28 days of life. Here we are discussing a case of Pediatric CVST in a 7-month-old baby boy who presented to Emergency Room (ER) with recurrent discrete episodes of vomiting, fever, seizures, drowsiness and respiratory distress. The fatal outcome in our child was attributed to delayed presentation in a tertiary care center, hence missed early diagnosis and treatment. In this child the CVST could be result of amalgamation of complex underlying ongoing multiple pathological processes: an acute systemic illness like sepsis, severe dehydration, undiagnosed and untreated complex congenital heart disease, tetralogy of fallot with osteum secondum atrial septal defect, worsening the coagulopathy. It takes this case even more unique. This discussion is to bring focus on the importance of knowledge about CVST amongst emergency physicians and primary care physicians, specially managing this rare disorder with flummox presentation mimicking other more common disorders, especially in pediatric and neonatal population where definitive history and chief complaints are often vague and difficult to obtain, making it more difficult to diagnose. We the authors hence reporting this case with intent to spread awareness of CVST, how to doubt it, detect it and then manage it, especially in places like Chhattisgarh, India, where CVST is not so uncommon. We believe early diagnosis, early presentation to tertiary care center with aggressive early treatment can significantly reduce the mortality. Should the parents brought the baby early to any tertiary care center owing to his complex deteriorating symptoms like high grade fever progressed to drowsiness and seizure episodes, could there be a different outcome for this child as well as his parents.

Quadrivalvar Rheumatic Cardiopathy in Tetralogy of Fallot in an Adult—A Case Report

Rheumatic involvement of all four heart valves is uncommon and its association with congenital heart disease is very rare. Tetralogy of Fallot is a frequent cyanotic congenital heart disease with a survival beyond middle age. Background of this case report described the rheumatic involvement of all four heart valves (quadrivalvar rheumatic cardiopathy) with stenotic lesions of semilunar valves (aortic and pulmonary valves) and regurgitant lesions of atrioventricular valves (mitral and tricuspid valves) in Tetralogy of Fallot in a 48-year old asymptomatic female, detected by transthoracic two dimensional echocardiography in Thoothukudi region of India.

USING CRYOPRESERVED HOMOGRAFT PERICARDIAL PATCH IN STAGED COMPLETE REPAIR FOR TETRALOGY OF FALLOT

Objective To compare the difference of effect while using homograt pericardium patch and Gore-rex patch in staged complete repair for Tetralogy of Fallot （TOF） to enlarge the right ventricular outflow tract （RVOT）. Methods Twenty-eight patients with TOF underwent the staged complete repair. Gore-rex patches were used to enlarge the RVOT of 13 patients, and cryopreserved homograft pericardium patches were used to enlarge the RVOT of 15 patients. The patients were followed up with 2-dimensional echocardiography and chest x-ray. Results One operative death in Gore-rex patch group, the mortality was 7. 7% ; 1 early postoperative death in cryopreserved homograft pericardium patch group, the mortality was 6. 7%. Between 2 groups, hemostasia time in operation room with significant difference （ P 〈 0. 01 ）, pericardial cavity drainage volume with difference （ P 〈 0. 05 ）. Gore-rex patch group was followed up 2 to 4.5 years, homograft pericardium patch group was followed up 0. 8 to 2.1 years. Echocardiography showed that there was significant difference of the residual obstruction at RVOT level （ P 〈 0. 01 ）. No calcification shadow was discovered on the chest x-ray of both groups. Conclusion Homograft pericardium is tissue with high density and intensity, its elasticity and compliance are good. Using homograft pericardium patch maybe helpful to decrease the residual obstruction of RVOT after operation. It can be adapted as a repairing material in cardiac surgery.

SURGICAL TREATMENT OF TETRALOGY OF FALLOT IN CHILDREN: A REPORT OF NO SURGICAL DEATH IN 115 CONSECUTIVE CASES

Objective A surgical team has performed total correction of Tetralogy of Fallot (TF) con-secutively in 115 patients without surgical, death. This paper presents an investigation of how to improve the sur-gical outcome. Methods This group included 115 children, the ages of these children at operation were from 9 months to 13 years (4.6 ± 2. 7 years), 47.8% of whom were younger than 3 years old. Associated anoma-lies included atresia of main pulmonary artery or unilateral pulmonary artery in 4 cases, a trial septal defect (ASD) and patent ductus arteriosus (PDA) in 11 cases. All patients have undergone total correction. Ventri-cular septal defects were closed with Dacron patches. Autologous-pericardial patches were used to enlarge the right ventricular outflow tract and pulmonary arteries. 102 cases (89%) needed transannular patches. Re-sults There was no surgical death and the patients have been followed up for 2 months to 4 years. One child died of cardiac arrhythmia 3 months after operation. The remaining patients recovered well. Conclusion The key points in improving the surgical outcome in TF patients lie in the improvement of surgical technique, total elimination of obstruction of right ventricular outflow tract and distal pulmonary arteries. Attention should be paid to the cardiopulmonary bypass and the postoperative care should also be emphasized.

Improving Right Ventricle Cardiac Function for Repaired Tetralogy of Fallot Patient with Contracting Bands: A Modelling Study

Objective Patients with repaired tetralogy of Fallot(rTOF)account for the majority of cases with late onset right ventricle(RV)failure.The current surgical approach,including pulmonary valve replacement/insertion(PVR),has yielded mixed results with some patients recover RV function and some do not.An innovative surgical approach was proposed to help ventricle to contract and improve RV function qualified by ejection fraction with one or more active contracting bands.Computational biomechanical modelling is a widely used method in cardiovascular study for investigation of mechanisms governing disease development,quantitative diagnostic and treatment strategies and improving surgical designs for better outcome.Muscle active contraction caused by zero-load sarcomere shortening leads to change of zero-load configurations.In lieu of experimenting using real surgery on animal or human,computational simulations(virtual surgery)were performed to test different band combination and insertion options to identify optimal surgery design and band insertion plan.Methods Cardiac magnetic resonance(CMR)data were obtained from one rTOF patient(sex:male,age:22.5 y)before pulmonary valve replacement surgery.The patient was suffering from RV dilation and dysfunction with RV end-systole volume 254.49ml and end-diastole volume 406.91 mL.A total of 15 computational RV/LV/Patch/Band combination models based on(CMR)imaging were constructed to investigate the influence of different band insertion surgery plans.These models included 5 different band insertion models combined and 3 different band contraction ratio(10%,15%and 20%band zero-stress length reduction).These models included 5 different band insertion models:Model 1 with one band at anterior to the middle of papillary muscle;Model 2 with one band at posterior to the middle of papillary muscle;Model 3 with 2 bands which are the ones from Models 1&2 combined;Model 4 with a band at the base of the papillary muscle;Model 5 with 3 bands which is a combination of Models 3&4.A pre-shrink process was performed on in-vivo begin-filling and end-systole MRI data to obtain diastole and systole zero4oad ventricle geometries.An extra 5%-8%shrinkage was applied to obtain corresponding systole zero-load geometry reflecting myocardium sarcomere shortening.The zero-load band length in systole was 10%,15%and 20%shorter than that in diastole according to their corresponding contraction ratio.The nonlinear Mooney-Rivlin model was used to describe the ventricle material properties with their material parameter values adjusted to match measured data with CMR.The band material properties were in the same scale with healthy right ventricle.The RV/LV/Band model construction and solution procedures were the same as described.Results Model 5 with band contraction ratio of 20%has the ability to improve RV ejection fraction to 41.07%,which represented a 3.61%absolute improvement,or 9.6%relative improvement using pre-PVR ejection fraction as the baseline number.The ejection fractions for Models 1-4 with band contraction ratio of 20%were 39.28%,39.47%,38.87%and 40.34%respectively.Compared to models with band contraction ratio15%and 20%,models with band contraction ratio 10%has the least ability on RV ejection fraction improvement with ejection fraction 38.28%,38.00%,38.81%,38.50%and 39.36%corresponding to Models 1-5.Conclusions This pilot work demonstrated that the band insertion surgery may have great potential to improve post-PVR RV cardiac function for patients with repaired TOF.More band contraction ratio and inserted band number may lead to better post-surgery outcome.Further investigations using in-vitro animal experiments and final patient studies are warranted.

Anisotropic Models of Human Pulmonary Root with Bicuspid Pulmonary Valve in Patients with Tetralogy of Fallot: Pulmonary Root Function Assessment and Mechanical Stress Analysis

Background Tetralogy of Fallot(TOF)is the most common cyanotic heart defect,accounting for 10%of all congenital defects.Pulmonary valve stenosis(PVS)is one common right ventricular outflow tract obstruction problem in patients with TOF.Congenital bicuspid pulmonary valve(BPV)is a condition of valvular stenosis,which morphologic feature is the presence of only two pulmonary leaflets instead of the normal tri-leaflet.Congenitally BPV are uncommon and the occurrence is often associated with TOF.Methods The three-dimensional geometric reconstruction of pulmonary root(PR)were based on well-accepted mathematical analytic models with physiological parameters obtained from a typical sample of the pulmonary root used in clinical surgery.The PR geometry included valvular leaflets,sinuses,interleaflet triangles and annulus.The dynamic computational models of normal PR with tri-leaflet and PR with BPV in patients with TOF were developed to investigate the effect of geometric structure of BPV on valve stress and strain distributions and the geometric orifice area.Mechanical properties of pulmonary valve leaflet were obtained from biaxial testing of human pulmonary valve left leaflet,and characterized by an anisotropic Mooney-Rivlin model.The complete cardiac cycle was simulated to observe valve leaflet dynamic stress and strain behaviors.Results Our results indicated that stress/strain distribution patterns of normal tri-leaflet pulmonary valve(TPV)and the BPV were different on valve leaflets when the valve was fully open,but they were similar when valves were completely closed.When the valve was fully open,the BPV maximum stress value on the leaflets was 218.1 kPa,which was 128.0%higher than of the normal TPV value(95.6 kPa),and BPV maximum strain value on the leaflets was 70.7%higher than of the normal TPV.The location of the maximum stress from TPV and BPV were also different,which were found at the bottom of the valve near the leaflet attachment for TPV and the vicinity of cusp of the fusion of two leaflets for BPV,respectively.During the valve was fully open,the stress distribution in the interleaflet triangles region of the PR was more asymmetric in the BPV model compared with that in the normal TPV model,and the largest change on the PR with the geometrical variations in the two models was 39.6%in maximum stress.This stress asymmetry indicates that BPV may be one of the causes of post-stenotic pulmonary artery dilatation and aneurysm in patients with TOF.The cusp of the BPV model showed significant eccentricity during peak systolic period,and its geometric orifice area value in the completely opened position of valve was reduced 57.5%from that of the normal TPV model.Conclusions Our initial results demonstrated that valve geometrical variations with BPV may be a potential risk factor linked to occurrence of PVS in patients with TOF.Computational models could be used as an effective tool to identifying possible linkage between pulmonary valve malformation disease development and biomechanical factors,better design of artificial valves and new surgical procedures without testing those on patients.Large-scale clinical studies are needed to validate these preliminary findings.